Available online a t www.pelagiaresearchlibrary.com Pelagia Research Library Advances in Applied Science Research, 2015, 6(6):187-193 ISSN: 0976-8610 CODEN (USA): AASRFC A comparative study of seaweed flora over a period of time with reference to climate change in Visakhapatnam Coast, Andhra Pradesh, India Vishnupriya Sowjanya I. and P. S. Raja Sekhar Department of Environmental Sciences, Andhra University, Visakhapatnam, A.P., India _____________________________________________________________________________________________ ABSTRACT A comparative study on present status of marine macro algal flora in relation to their occurrence, distribution and diversity was carried out at along the Visakhapatnam coast intertidal shores areas of Bay of Bengal, East coast of India over a period of five decades with reference to climate change. A total of 48 seaweeds species were recorded, of which 18 species (37%) belong to Chlorophyta, 9 species (19%) belong to Phaeophyta and 21 species (44%) belong to Rhodophyta. A total of 10 macroalgae species were newly recorded, while, 41 species were found to be absent during the present study when compared to 1964 data obtained from this coast. In the present study, the impacts of Hudhud, severe tropical cyclone on intertidal macro algae was observed. Cyclone development in East coast of India was observed in the months of September – November, when prominent growth of macroalgae was recorded. Climate change not only increases the impact of environmental stressors but also intensify their frequency of occurrence. Keywords: Seaweeds, Visakhapatnam coast, Bay of Bengal, Climate change, Hudhud cyclone. _____________________________________________________________________________________________ INTRODUCTION Seaweeds are macroscopic marine algae that are differentiated into three distinct divisions, Chlorophyta (green algae), Phaeophyta (brown algae) and Rhodophyta (red algae). Seaweeds, known as macroalgae, are among the most important primary producers and act as ecological engineers on rocky coasts of the world’s ocean. Most of the seaweeds are growing in the intertidal zone throughout the world although some occupied the supra-littoral and sub- littoral zones of the sea. In this paper, we consider the vulnerability of intertidal macroalgae to climate change in terms of the vulnerability of species composition and distributions, with reference to five decades data. Climate change refers to the complex environmental changes caused by increasing emissions of CO 2 and other greenhouse gases to the atmosphere, and they have great consequences for marine life forms [3]. Climate change will reduce the resilience of macroalgal habitats to other stressors such as pollution. Extreme events (storms, heat waves, etc) will increase in frequency and magnitude and drive shifts in species’ distributions and interactions [8]. However, it is not only the biodiversity of algae themselves that is under threat; macroalgae are foundation species that facilitate the existence of a myriad of equally unique associated marine life. International studies suggest that climate driven loss of macroalgal canopies to waves may have cascading effects on associated ecosystems and food webs. In the present study, data on macro algae diversity along the Visakhapatnam coast was collected and compared with previous data over a period of five decades to assess the changes in relation to climate change and associated environmental factors. Study Area: The study area Visakhapatnam coast was located in North Eastern part of Andhra Pradesh between 17 o - 15' and 18 o-32' Northern latitude and 18 o - 54' and 83 o - 30' in Eastern longitudes. Outcrops of rocky boulders on the Visakhapatnam coastline, extending over 132 km, offer a variety of habitats for the growth of marine algae. 187 Pelagia Research Library Vishnupriya Sowjanya I. and P. S. Raja Sekhar Adv. Appl. Sci. Res., 2015, 6(6):187-193 _____________________________________________________________________________ Considering the variations in the nature of the substratum and the associated ecological conditions, ten field stations were selected along the coastline for algal collection and detailed study. There are two river openings into the sea in the vicinity of field station I (Varaha River) and station X (Gosthani River) (Figure 1). Field Station Study area/ Site Substratum available for algal growth I Bangarammapalem Large rocky boulders II Rambilli Rocky boulders III Pudimadaka Rocky platform IV Appikonda Large rocky boulders V Yarada Rocky platform with small basin like pools VI Ramakrishna beach Shingle area VII Tenneti Park Large rocky platform with small basin like pools VIII Rushikonda Shingle area IX Thotlakonda Large rocky platform with tidal pools X Bheemunipatnam Large rocky platform with small basin like pools Figure 1: Map showing field stations at the Visakhapatnam coast MATERIALS AND METHODS Field data was obtained during leap tides (low height tides) from May, 2013 to January, 2015. The whole year is classified into four seasons i.e., May-July, August-October, November-January and February-April for our consideration. Each field site was sampled throughout the year seasonally for species cover and species presence or absence. Species cover is sampled by using quadrat sampling method. Species composition and coverage were obtained from the data collected by using 20 randomly selected quadrat size of 50cmX50cm with 25 subdivisions following the method developed by [9]. Seaweed species, coverage and corresponding indices (referring to Table 1) in each of the 25 subdivisions were recorded. The parameter obtained from each quadrat with respect to coverage (C; expressed as %) was used to compute for the area in the substrate occupied by the species. For convenience, the index numbers: 5, 4, 3, 2, 1 were used for recording data in the field as in the Table 1. Species Richness (SR), Shannon-Weiner Diversity Index (H 1) and Evenness (e) were also calculated. C(`%)=(qn 5xc 5)+(qn 4xc 4)+(qn 3xc 3)+(qn 2xc 2)+(qn 1xc 1) where, qn n is the number of subdivisions in which a species appeared to have the corresponding area described in the Table 1. 188 Pelagia Research Library Vishnupriya Sowjanya I. and P. S. Raja Sekhar Adv. Appl. Sci. Res., 2015, 6(6):187-193 _____________________________________________________________________________ Table 1. Indices of the degree of macro algae cover and its representative multiplier Indices Degree of algal cover on the substratum Multiplier, C n 5 Covering 1/2-1 of the substratum surface 3.0 4 Covering 1/4-1/2 of the substratum surface 1.5 3 Covering 1/8-1/4 of the substratum surface 0.75 2 Covering 1/16-1/8 of the substratum surface 0.375 1 Covering less than 1/16 of the substratum surface 0.1875 Representative seaweed samples were preserved in 5.0% saline formalin solution and were identified with descriptions and the taxonomic keys provided by Umamaheswara Rao (1964, 1970); Narasimha Rao (1989), Prasanna Lakshmi & Narasimha Rao (2009) and Satya Rao et al., (2011). The observed data from the present study was correlated with pervious data over a period of five decades to notice the changes in diversity and species composition of macro algae at Visakhapatnam coast. RESULTS AND DISCUSSION Visakhapatnam coastline provides a good habitat for macroalgae with semidiurnal tides (i.e., two spring tides and two leap tides a day). A total of 48 seaweeds species were recorded in the coast during the study period, of which 18 species (36%) belong to Chlorophyta, 9 species (19%) belong to Phaeophyta and 21 species (45%) belong to Rhodophyta. The species viz . Ulva fasciata , Ulva lactuca, Enteromorpha compressa , Chaetomorpha antennina , Cladophora socialis , Spongomorpha indica , Amphiroa fragilissima, Gracilaria corticata, Gracilaria textori, Padina tetrastromatica and Caulerpa taxifolia were found to be dominant in rocky shores and other submerged hard surfaces of Visakhapatnam coast (Table 2). The earlier studies [2], [6], [7] have reported 80 species of marine algae from Visakhapatnam coast, whereas, [4], [5] have recorded 31 and 39 species of macro algae respectively from Visakhapatnam coast. After five decades, the species richness was relatively low when compared to the macroalgae studied at the same coast in 1964 (Figure 2). A total of 10 macroalgae species were newly recorded, while, 41 species were found to be absent in 2014 when compared to 1964 data obtained from this coast (Table 3). The decline percentage was higher in Rhodophyta (23 species; 52.2%), followed by Phaeophyta (7 species; 43.8%) and Chlorophyta (2 species; 10.0%). The lowest decline percentage of Chlorophyta members in course of five decades indicates their resilience capability for environmental stressors. Figure 2: Graph showing decline of macroalgae species richness at Visakhapatnam coast over five decades Species richness and percentage cover was observed that highest in Season III (November-January) followed by Season IV (February-April). Low values of percentage cover and species richness was observed in Season II (August-October) and Season I (May-July). In all seasons highest Shannon-Weiner diversity index was observed for Station III with 2.808, 3.078, 3.439 and 3.434. And lowest Shannon-Weiner diversity index was observed for Station 189 Pelagia Research Library Vishnupriya Sowjanya I. and P. S. Raja Sekhar Adv. Appl. Sci. Res., 2015, 6(6):187-193 _____________________________________________________________________________ IV with 0.688, 0.591, 0.876 and